1. Field of the Invention
The field of the present invention is that of motor vehicle lighting. In general, the invention relates to a lighting system which is based on light emitting diodes, or LEDs. More specifically, the invention relates to a device for measurement of characteristics parameters of a light emitting diode. The invention also relates to a module to control the electrical supply to this diode, and its method.
A light emitting diode (or LED) is an electronic component which can emit light when an electric current passes through it. Significant advances have made possible major new applications such as in lighting, including in motor vehicle lighting. In fact the diodes can be used to provide light, and this is one of the headlight technology applications which is continually being developed.
2. Description of the Related Art
Certain vehicles are therefore now equipped with light emitting diodes of this type. Typically, the LEDs can be organized into assemblies, with each assembly of LEDs fulfilling at least one lighting function, such as high-beam or low-beam lights, for example.
The current of the LEDs must be controlled, in other words the control circuit of the LEDs must be able to define the current which passes through them, independently of the number of LEDs placed in series. In addition, the relationship which associates the voltage and supply current of the LEDs is not linear. Thus, a small increase in voltage applied to the LED can give rise to a substantial increase in the current, and therefore in the flow of light.
More importantly, an excessive increase in the voltage at the terminals of the LEDs gives rise to an excessively great passage of current, which can damage the component.
It is therefore essential to have a system to control the supply to the LEDs in order to control the flow of light, and generate the variation of the flow of the LEDs (dimming).
For this purpose, the conventional control system is often an LED driver. This component, which controls the supply to the LEDs on the basis of functioning parameters, in general requires the present of measurement means (in particular in order to avoid excessive heating of the LEDs), which consist of a complex circuit, normally with at least one inductor, capacitors, one or more diodes, a plurality of different power transistors, and resistors, for each assembly of LEDs.
Consequently, these known control circuits comprise complicated circuits and/or a plurality of quite complex electrical components.